NCC 2025 Implications for Waterproofing

February 2026 saw the release of the Final Draft of National Construction Code 2025. Waterproofing Integrity have been interpreting the implications and can share the below.

What can Waterproofing Integrity tell you about the implications for waterproofing under NCC 2025?

As indicated on the Australian Building Codes Board website to announce the Final Draft, Water management under Volume One Section F (Health and amenity) is the headline item. With these changes, the primary considerations are around the clauses of Section F which impact how water is prevented from entering a building or is managed when reaching a building. The sources includes both rain and groundwater with implications on basements and external waterproofed areas. As was the case under NCC 2022, the clauses of the NCC override the waterproofing Standards of AS37430 and AS4654.2

What NCC 2025 changes impact waterproofing?

Waterproofing Integrity Director David Previte prepared this short video in May 2024 as a quick summary of the perceived implications and with grammatical changes to the clauses, the implications remain the same.

In summary, the following are the six considerations that Waterproofing Integrity have identified:

Point 1: Class 7 and 8 buildings are no longer exempt from waterproofing performance requirements
Point 2: Structural falls must have a minimum gradient of 1 over 80 for external areas
Point 3: 70mm structural step downs and integral hobs required around building elements
Point 4: Exposed joints must be located at ridgeline of falls with hobs on either side
Point 5: Waterproofing membranes must be applied directly to the structural substrate
Point 6: Floor finishes to be self-draining or directly fixed to waterproofing membrane

How do I comply with NCC 2025 if the building is already designed?

For many, economic pressures, labour shortages and buyer demand have meant that projects have been approved but not yet commenced. With the exception of previously designed Government work and some Victorian projects that have achieved significant design completion to lock in previous versions of the NCC, projects that have not commenced to lock in NCC 2022 prior to the adoption of NCC 2025, will likely need to adopt and apply NCC 2025. Of course, consult your certifying authority and don't just take our word for it.

Subject to the design of the project and how many of the above apply, there may be a number of implications around structural, hydraulic, facade and finishes. All elements that waterproofing compliance considerations interact with and elements that Waterproofing Integrity have consulted on with clients for over 750 projects. Waterproofing Integrity are able to find working solutions to each of the above implications and how it impacts your project. The penthouse of the residential tower need not be sacrificed because the NCC implores thicker slabs for falls and causes the building to exceed its approved height.

What do I need to comply with NCC 2025 waterproofing implications?

An excellent concreter. To achieve 1:80 falls consistently across large expanses is no easy task. With the requirement for membrane being applied to the structural substrate, there is no allowance for a substrate other than concrete. No screed, no topping, no leveller.

Prior to that however, what should be considered is effective waterproofing design considerations by qualified and experienced personnel to identify the above considerations, how they apply to the project, its unique site conditions and building design.

For basements, Waterproofing Integrity have a dedicated basement team of Engineers that can address the waterproofing performance requirements of below ground structures. If Class 7 and 8 buildings are no longer exempt, but there is no deemed to satisfy pathway, then the design would need to be assessed on its performance requirements as a Performance Solution.

Achieving compliance with the above ground elements may require some further considerations around layouts, use of materials and how the building manages water effectively. Waterproofing Integrity have been working with a number of projects designing to NCC 2025 already and are finding compliant outcomes. Performance Solutions are something that can be entertained but finding deemed to satisfy outcomes is possible with effective engagement early enough in the design phase. Pouring concrete slabs and then thinking waterproofing design is too late as costly rework and time delays occur to reach compliant outcomes.

When will the NCC 2025 Waterproofing Implications come into effect?

Now that the Final Draft has been made available, State Building Ministers will evaluate and propose how their respective states react in adopting NCC 2025. With the cycle following updates in May every three years and the next NCC slated for 2029, there may only be three months notice period for these changes to apply. We have known about them for over 18 months and the clause intentions remain largely unchanged. So subject to which state the project is in will determine when NCC 2025, and to what extent. As history shows, states have adopted NCC updates in full or partially. Some states accept some elements and not others with Accessible Housing requirements being one such consideration under NCC 2022 that was not uniformly adopted across Australia.

Which Australian States will adopt NCC 2025 when?

We can be purely speculative to suggest that NSW, ACT and Victoria are the most likely to adopt NCC 2025 in mid-2026. Whether that is in full, staggered adoption or selective in what applies will remain to be seen. Queensland may be next likely with South Australia, Tasmania and Northern Territory to follow. Western Australia are very unlikely to adopt NCC 2025 less than 12 months after adopting NCC 2022 so will likely be in 2028 following recent cycles.

How do I find out more?

Waterproofing Integrity have provided a number of information sessions to date on the topic through direct meetings and conference presentations. We are looking at providing more in this regard in early 2026 but please reach out on 1300 025 944 or sales@waterproofingintegrity.com.au to discuss with our team how the above applies to your current or future project and what we can do to assist.

With resources in Sydney, Melbourne, Brisbane and Newcastle we can facilitate online and onsite consultation.